MESOSCALE PRECIPITATION DISCUSSION 0085
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
319 AM EDT FRI MAY 15 2015
 
AREAS AFFECTED...SOUTH-CENTRAL TX... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 150718Z - 151203Z
 
SUMMARY...A PERSISTENT AREA OF CONVECTION SHOULD CONTINUE TO
AFFECT A REGION JUST EAST OF THE BIG BEND. FLASH FLOODING HAS
ALREADY OCCURRED AND WILL REMAIN A THREAT THROUGH AT LEAST 12Z. 

DISCUSSION...A CONVECTIVE COMPLEX WHICH DEVELOPED AROUND 02Z HAS
GENERALLY MAINTAINED ITSELF INTO THE OVERNIGHT HOURS WITH RADAR
ESTIMATES OF 3 TO 5 INCHES. THIS HEAVY RAINFALL HAS LED TO AT
LEAST ONE FLASH FLOOD REPORT IN THE WESTERN QUADRANT OF THE
AUSTIN/SAN ANTONIO CWA. THE KDFX RADAR IMAGERY SHOWED CELL MOTIONS
GENERALLY AROUND 1O TO 15 KNOTS TO THE EAST WHICH IS CONSISTENT
WITH THE 06Z RAP CORFIDI VECTORS. HOWEVER...CONVECTION HAS
CONTINUALLY BEEN REGENERATED ALONG THE RIO GRANDE WHERE LOW-LEVEL
MOISTURE FLUXES HAVE BEEN MAXIMIZED.

BASED ON THE 06Z RAP INSTABILITY PROFILES...THE INFLOW AIR REMAINS
VERY UNSTABLE WITH MUCAPE VALUES ABOVE 2000 J/KG FEEDING INTO THE
REGION. THIS CONTINUES TO WORK IN CONJUNCTION WITH A MOISTURE RICH
AIR MASS WITH PWATS IN THE 1.50 TO 1.75 INCH RANGE JUST EAST OF
THE BIG BEND. DURING THE NEXT SEVERAL HOURS...THIS PERSISTENT FEED
OF MOISTURE-LADEN AIR INTO THE REGION DOES NOT CHANGE A WHOLE LOT
ALTHOUGH THE INSTABILITY DOES WANE SLIGHTLY IN TIME. HOWEVER...DO
BELIEVE THIS ACTIVE NIGHT OF CONVECTION SHOULD CONTINUE FOR THE
NEXT FEW HOURS...PERHAPS UNTIL 12Z. THIS SUPPORTS WHAT A MAJORITY
OF THE HIGH-RESOLUTION MODELS HAVE BEEN SHOWING....PARTICULARLY
THE 06Z HRRR. 


RUBIN-OSTER

ATTN...WFO...CRP...EWX...SJT...

ATTN...RFC...WGRFC...

LAT...LON   30589931 29939765 29139772 28639822 28009885 
            27869951 28210015 28990072 29660140 30550095